Re: [Qemu-devel] [PATCH v5 6/8] target/mips: Define the R5900 CPU

Re: [Qemu-devel] [PATCH v5 6/8] target/mips: Define the R5900 CPU

[Fredrik Noring]

Hi Maciej,

>  The C790 is a follow-up to the R5900.  The R5900 has an FPU that is not 
> compliant to the IEEE 754 standard for floating-point arithmetic.  It 
> doesn't implement exceptions, infinities, NaNs or denormals.  It doesn't 
> implement the the double format either, but that is really tangential, 
> because the same was the case with the IDT R4650, which had a standard 
> IEEE 754 FPU, but no double format either.  Finally it has some anomalies 
> in the FP instruction set; not all opcode encodings are standard.

Do you know where one might find a list of the nonstandard FP instructions?

The command

% grep 'FP_.*EE' binutils/opcodes/mips-opc.c

gives a list of candidates, I suppose?

Fredrik

Re: [Qemu-devel] [PATCH v5 6/8] target/mips: Define the R5900 CPU

[Maciej W. Rozycki]

Hi Fredrik,

> >  The C790 is a follow-up to the R5900.  The R5900 has an FPU that is not 
> > compliant to the IEEE 754 standard for floating-point arithmetic.  It 
> > doesn't implement exceptions, infinities, NaNs or denormals.  It doesn't 
> > implement the the double format either, but that is really tangential, 
> > because the same was the case with the IDT R4650, which had a standard 
> > IEEE 754 FPU, but no double format either.  Finally it has some anomalies 
> > in the FP instruction set; not all opcode encodings are standard.
> 
> Do you know where one might find a list of the nonstandard FP instructions?
> 
> The command
> 
> % grep 'FP_.*EE' binutils/opcodes/mips-opc.c
> 
> gives a list of candidates, I suppose?

 Yeah, those that have EE in `membership' are extra and those that have EE 
in `exclusions' are missing.

 See also: <https://sourceware.org/ml/binutils/2012-11/msg00360.html>.

  Maciej